As technology has been developed, semiconductor chips have been highly integrated. In general, a semiconductor chip fabricated through a micro-fabrication process undergoes an electrical test before packaging process to sort out defective products. For the electrical test, a probe card is used to connect between a tester and an electrode pad of the semiconductor chip.
A probe (also known as a contactor or needle) installed in the probe card may be classified into a cantilever type and a vertical type. The probe should have a structure that can absorb a step difference between the electrode pads, and at the same time should eliminate native oxides on the electrode pad.
In order to satisfy these requirements, a micro contact probe having a simple single beam shape as shown in FIG. 1 has been conventionally disclosed as a typical cantilever-type probe. As shown in FIG. 1, the conventional cantilever-type micro contact probe is formed of a connection portion 101 connected to a probe card (not shown), an extending portion 103 extending in a side direction from the connection portion 101, and a contact portion 105 having a tip 107 formed to protrude from an end portion of the extending portion 103 to contact a pad of a semiconductor chip.
As shown in FIG. 1, the cantilever-type micro contact probe has a single beam because the connection portion 101 of the conventional cantilever-type micro contact probe is extended in the up and down direction, that is, a vertical direction, and the extending portion 103 is extending in the left and right direction, that is, a horizontal direction.
Since the conventional cantilever-type micro contact probe is formed in the single beam shape, stress concentration may easily occur so that plastic deformation is easily generated. In addition, the conventional cantilever-type micro contact probe cannot be used for a small electrode pad due to an excessive scrub length.
In order to overcome the drawbacks of the cantilever-type micro contact probe having a single beam, the cantilever-type micro contact probe having a dual beam of FIG. 2 and FIG. 3 have been disclosed.
As shown in FIG. 2, the conventional cantilever-type micro contact probe having a dual beam is formed of a connection portion 111 connected to a probe card (not shown), an extending portion 113 extending in a side direction from the connection portion 111, and a contact portion 115 having a tip 117 formed to protrude from an end portion of the extending portion 113 to contact a pad of a semiconductor chip.
In FIG. 2, the extending portion 113 includes an upper beam 113a and a lower beam 113b arranged up and down, and the extending portion 113 has a dual beam shape by forming a long slit-shape opening 113c between the upper and lower beams 113a and 113b. 
According to the conventional cantilever-type micro contact probe having a dual beam of FIG. 2, when the tip 117 of the contact portion 115 contacts the electrode pad of the semiconductor chip so that a load is applied to the probe during testing of the semiconductor chip, the length of the scrub may be reduced compared to the conventional probe of FIG. 1.
However, the conventional cantilever-type micro contact probe having a dual beam of FIG. 2 may have a stress concentration problem when the probe is deformed due to external force.
As shown in FIG. 3, a conventional cantilever-type micro contact probe having a bellows-shaped dual beam is formed of a connection portion 121 connected to a probe card (not shown), an extending portion 123 extending in a side direction from the connection portion 121, and a contact portion 125 having a tip 127 formed to protrude from an end portion of the extending portion 123 to contact an electrode pad of a semiconductor chip.
In FIG. 3, the extending portion 123 includes an upper beam 123a and a lower beam 123b arranged up and down, and the extending portion 123 has a dual beam shape by forming a long slit-shape opening 123c between the upper and lower beams 123a and 123b. 
In this case, the shape of the extending portion 123 has a bellow-shaped dual beam that bends in different directions while having at least one inflection point rather than having a straight dual beam shape, as shown in FIG. 2.
According to the conventional cantilever-type micro contact probe having a dual beam of FIG. 3, when the tip 127 of the contact portion 125 contacts the electrode pad of the semiconductor chip so that a load is applied to the probe during testing of the semiconductor chip, the length of the scrub may be reduced compared to the conventional probe of FIG. 1, and particularly, out of plane behavior and stress concentration can be reduced because the extending portion 123 has the bellows shape.
However, the conventional cantilever-type micro contact probe having a bellows shaped dual beam shown in FIG. 3 needs to have more stress relaxation when the probe is deformed due to external force, and it cannot be easily designed due to too many design variables and the complicated shape.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.